text: /**
   * A plugin which enables rendering of math equations inside
   * of reveal.js slides. Essentially a thin wrapper for MathJax.
   *
   * @author Hakim El Hattab
   */
  export const MathJax2 = () => {
  
  	// The reveal.js instance this plugin is attached to
  	let deck;
  
  	let defaultOptions = {
  		messageStyle: 'none',
  		tex2jax: {
  			inlineMath: [ [ '$', '$' ], [ '\\(', '\\)' ] ],
  			skipTags: [ 'script', 'noscript', 'style', 'textarea', 'pre' ]
  		},
  		skipStartupTypeset: true
  	};
  
  	function loadScript( url, callback ) {
  
  		let head = document.querySelector( 'head' );
  		let script = document.createElement( 'script' );
  		script.type = 'text/javascript';
  		script.src = url;
  
  		// Wrapper for callback to make sure it only fires once
  		let finish = () => {
  			if( typeof callback === 'function' ) {
  				callback.call();
  				callback = null;
  			}
  		}
  
  		script.onload = finish;
  
  		// IE
  		script.onreadystatechange = () => {
  			if ( this.readyState === 'loaded' ) {
  				finish();
  			}
  		}
  
  		// Normal browsers
  		head.appendChild( script );
  
  	}
  
  	return {
  		id: 'mathjax2',
  
  		init: function( reveal ) {
  
  			deck = reveal;
  
  			let revealOptions = deck.getConfig().mathjax2 || deck.getConfig().math || {};
  
  			let options = { ...defaultOptions, ...revealOptions };
  			let mathjax = options.mathjax || 'https://cdn.jsdelivr.net/npm/mathjax@2/MathJax.js';
  			let config = options.config || 'TeX-AMS_HTML-full';
  			let url = mathjax + '?config=' + config;
  
  			options.tex2jax = { ...defaultOptions.tex2jax, ...revealOptions.tex2jax };
  
  			options.mathjax = options.config = null;
  
  			loadScript( url, function() {
  
  				MathJax.Hub.Config( options );
  
  				// Typeset followed by an immediate reveal.js layout since
  				// the typesetting process could affect slide height
  				MathJax.Hub.Queue( [ 'Typeset', MathJax.Hub, deck.getRevealElement() ] );
  				MathJax.Hub.Queue( deck.layout );
  
  				// Reprocess equations in slides when they turn visible
  				deck.on( 'slidechanged', function( event ) {
  
  					MathJax.Hub.Queue( [ 'Typeset', MathJax.Hub, event.currentSlide ] );
  
  				} );
  
  			} );
  
  		}
  	}
  
  };
  